The conflict between bikes and cars on San Francisco streets may never be settled. But for at least one night this week there was a truce.

The Ride of Silence was a slow, 12 1/2-mile roll through the city's neighborhoods by 30 local bike riders. It was meant to be a reminder of the unfortunate physics that result when large motor vehicles collide with bikes - cyclists don't have a chance.

Devon Warner, one of the organizers, says she was moved to act when her friend Dave Martinez was hit by a truck while commuting to work near Fremont. She says the news report of the fatal accident elicited angry comments about out-of-control bikers.

"I just thought, holy hell, he wasn't a road obstruction," Warner said. "He was a decent guy with a wife and teenage kids."

The ride was San Francisco's contribution to a day of remembrance that was first organized 10 years ago. That's when endurance cyclist Larry Schwartz was struck and killed by the mirror of a passing bus in Dallas.

Over 1,000 riders showed up for that first ride, and since then the event has gone global. Wednesday night there were over 368 rides in 50 states and 26 countries - from Antarctica to Pakistan to Hong Kong.

All of which is relevant in San Francisco, where bike ridership has increased 71 percent since 2006, and in the same period, collisions resulting in injuries increased 84 percent. Across the country, the National Highway Traffic Safety Administration said two years ago that bicycle fatalities were up 8.7 percent. As those totals grow, the Ride of Silence along the bumpy, potholed San Francisco streets made the numbers personal.

In all there were 10 stops - undistinguished street corners San Franciscans pass every day, unaware that a bicyclist died there.

Co-organizer Ramona Wheelright, who started the San Francisco version of the ride in 2009, handed out cards with a montage of the faces of victims. They all looked young, fit and engaged. Someone you'd like to take a bike ride with.

Among them was Renata Gonzalez, an art student, who was riding up Market Street when a pickup truck hit her at Octavia. Gonzalez's small dog, Ari, who had been riding in a basket on the handlebars, was killed instantly. Gonzalez suffered brain damage, went into a coma and survived three years before dying at her parents' home in San Antonio. She was 30 when she died.

"She was just full of life, a rising star," said her friend from art school, Emily Lounsbury. "And Ari, a little long-haired Chihuahua, was just the world to her. I think about her all the time."

We also stopped at Third and King streets, site of the most recent deadly accident. Diana Sullivan, 48, was hit by a concrete truck near AT&T Park on the morning of Feb. 3.

"I was here that day," said Peter Chu, who was among the Ride of Silence participants. "It was Fan Appreciation Day. There were thousands of people."

Sullivan is remembered by a white "ghost bike," chained to a post at the intersection. Ghost bikes often have become a symbol of the rides. Although they are not always placed at the site of a fatal accident, and are sometimes removed by the city, seeing them is a telling reminder.

"When you know what they are, you tend to look for them," said Miles Cooper, another rider. "I've seen them in other countries, even Lima, Peru."

With so many sad stories, you'd think the riders would begin to wonder about urban cycling. But art professor Anthony Ryan, who was hit by a car on the way to work at San Francisco State, says that isn't going to happen.

"All implants," he said, tapping his upper row of front teeth. "I landed face first, and my teeth were all over the street. But I haven't quit. I sold my car three years ago. I guess I'm either committed or I should be committed."

But there were plenty of reminders of the danger. On the way to a site out in the Richmond District, the group paused at a four-way stop. As we started to pedal out into the intersection, a silver SUV came down the hill. The woman driving slowed down, looked directly at the riders, then hit the gas and powered through the stop sign. She looked utterly unconcerned.